The mice (D1 and D3 receptor mutants and GRK4 wild type and A142V transgenes) required for project by Jose in this PPG will be bred and maintained by the Animal Core. Colonies to support adult mice of 8-14 weeks will be developed from initial breeders. Heterozygous (+/-) mice will be bred to provide homozygous (+/+) wild type, heterozygous (+/-) and homozygous (-/-) deleted mice in the same litter. The Animal Core has in place functioning breeding colonies and has a detailed plan that specifies the number of mice necessary to support the proposed research. The Core has the infrastructure in place to maintain breeding information in a database that catalogues ear tag identification and breeding history and numerous other parameters. The Animal Core will collect blood and/or tail tissue from weanling mice for genotyping in the Analytical Core. The Animal Core will also measure the conscious mean arterial blood pressure directly by radio-telemetry in a subset of each single-gene deleted or transgenic strain. The Animal Core will provide all technical support for all protocols involving animals and assure that the PPG is in compliance with all institutional regulations regarding animal breeding and experimental use.